Submitted to: Avian Diseases
Publication Type: Peer reviewed journal
Publication Acceptance Date: 2/24/2003
Publication Date: 12/31/2003
Citation: LEE, L.F., WITTER, R.L., REDDY, S.M., WU, P., YANAGIDA, N., YOSHIDA, S. PROTECTION AND SYNERGISM BY RECOMBINANT FOWL POX VACCINES EXPRESSING MULTIPLE GENES FROM MAREK'S DISEASE VIRUS. AVIAN DISEASES. 2003. V. 47. P. 549-558. Interpretive Summary: Marek's disease (MD), a virus induced cancer-like disease of chickens, is considered as a major disease problem in commercial poultry. Vaccination has dramatically reduced the incidence of the disease, but very little is known about the basic mechanisms involved in the induction of disease. The objective of this research was to molecularly characterize the causative virus so that successful programs to control the disease can be developed. We identified two hereditary elements (genes) named gB and gI that control important virus functions such as induction of protective immunity. This important genetic information about MD virus will undoubtedly help scientists in academia and industry understand the function of the various MD virus genes and eventually lead to better control of the disease.
Technical Abstract: Recombinant fowlpox viruses (rFPV) were constructed to express genes from serotype 1 Marek's disease virus (MDV) coding for glycoproteins B, E, I, H, L, UL32 (gB1, gE, gI, gH, gL and gp82). An additional rFPV was constructed to contain four MDV genes (gB1, gE, gI and gp82). These rFPVs alone and rFPVs containing multiple genes were evaluated for their ability to protect maternal antibody positive (ab+) chickens against challenge with highly virulent MDV isolates. The protective efficacy was also compared to that of prototype MD vaccines. Protection was induced in ab+ chickens by rFPV expressing gB, gI and multiple genes. In contrast, the rFPV/gE, rFPV/gH, rFPV/gL and rFPV/UL32 constructs did not induce any significant protection against MDV challenge compared to 42% for rFPV/gB1 and 43% for rFPV/gI and 37% for cell-associated HVT. Levels of protection by rFPV/gB1 and rFPV/gI was comparable with HVT. The level of protection by rFPVs containing multiple genes (70%) was significantly higher than with single gene (40%). When rFPV/gB1gIgEUL32 was combined with cell-associated HVT,protection was 94% and enhanced by about 80% compared to the monovalent vaccine. The mean level of HVT protection was 54% compared to 90% for the HVT + SB-1 bivalent vaccine. Relatively high protection (83%) and enhancement (97%) was also observed between rFPV/gB1 and HVT. Levels of protection by rFPVs with multiple genes were similar to those of conventional bivalent MD vaccines containing serotype 2 and 3 viruses.